This invention relates to keyboards for electric typewriters, cathode ray terminals, word processing equipment, and other devices that use a keyboard to transfer natural language texts to a machine.
An earlier U.S. Pat. No. 3,929,216 discusses the limiations of the universal ("qwerty") typewriter keyboard, and the linguistic and kinesthetic factors governing keyboard design. Curilinear keyboards are revealed in this patent for six languages based on the statistical properties of character sequences occuring in these languages. A second U.S. Pat. No. 3,945,482 discloses curvilinear keyboards for eight languages that employ vertically oriented keys which are assigned medium frequency characters.
The keyboards disclosed in these patents ignore the traditional spacial location of keys on the standard keyboard, and assign vowels and consonants to opposite sides of the keyboard to minimize the number of successive strokes made by the same hand. Experimental observation indicates, however, that keyboard learning can be accelerated by placing vowels and consonants on both sides of the keyboard to maximize the number of successive strokes made by the same hand. Furhermore, the expense of introducing a new keyboard may be reduced by retaining the straight parallel key rows and key locations used on the standard keyboard.